A drawback of open-jet filling is that as the rotor of a filling machine rotates, centrifugal force deflects the open filling-jet outwards and away from this machine axis.
One way to reduce this deflection is to use a very large rotor or to avoid spinning the rotor too fast.
A known way to compensate for the deflection is to make the container's mouth large enough so that even if centrifugal force deflects the jet, it still manages to enter the mouth.
A difficulty with this procedure is that if one uses a wide jet so as to achieve faster filling, there is a high risk of missing the mouth with some part of the jet. A narrow filling jet is less likely to miss the mouth. But one cannot fill as fast with a narrow jet.